Controversy over Neurontin data

Researchers claim that Pfizer used selective outcome reporting in published trial reports

Pfizer misrepresented trial data for the off-label use of its epilepsy treatment Neurontin to emphasise favourable results, according to researchers.

When comparing internal documents from Pfizer and Parke-Davis with published data from 12 clinical trials, researchers found inconsistencies between what was published and original trial data. In eight of 12 reported trials, the primary outcome defined in the published report differed from the described protocol, researchers stated in an article in the New England Journal of Medicine (NEJM).

Other discrepancies include the introduction of a new primary outcome in six of the trials, failure to distinguish between primary and secondary outcomes in two trials, relegation of primary outcomes in two trials and failure to report one or more protocol-defined primary outcomes in five trials.

According to the report authors, who include Kay Dickersin, Professor of epidemiology at the John Hopkins Bloomberg School of Public Health, the identified practice of selective outcomes reporting for trials of off-label use of Neurontin threatens the validity of evidence for the effectiveness of off-label interventions.

The researchers gained access to Pfizer internal documents as a result of litigation against the company and Parke-Davis for promoting Neurontin for off-label uses or those not approved by the US Food and Drug Administration (FDA), the NEJM article states.

Dickersin agreed to be an expert witness for the prosecution during the court case only if she would be allowed to publish information from unsealed documents.

Pfizer refutes the claims made in the article, branding them “untrue”. The company has also stated that it believes the NEJM review suffers from “significant bias, insufficient data, poor methodology” and lacks scientific credibility.